Category Archives: New International Cloud Atlas

April’s been kind of a weather dud here in Catalina so far (no rain so far, and the chance on the 20th, mentioned here some weeks ago, has receded to Utah and points north), so lets take a look at how May is shaping up, only two weeks ahead:

Its possible there is a photo from Catalina, Arizona! I have not checked yet. Its just been published by the World Meteorological Organization of the United Nations. Still needs a little work, but overall is VERY, very nice. Came out out on March 23rd, so we’re a little behind here as usual. The thing that makes it different from prior and sometimes flawed atlases is that each photo is accompanied by some weather data and in many cases maps, radar or satellite imagery at the time of the photo.

Some new expressions to toss around to your fellow cloud-centric folk are things like “Cirrus anthrogenitus”–Cirrus evolved from contrails and “Cumulus flammogenitus”, a Cumulus formed at the top of a fire, something we used to call, “pyrocumulus”, an unofficial term that somehow seems preferable to “flammo”.

However, something that has drawn great attention over the past 20 years or so was not given a name, aircraft-produced ice in Altocumulus and Cirrocumulus clouds, which have been referred to by Heymsfield and colleagues as “hole punch clouds.”1

Ice canals amid Altocumulus are also fairly common. Ironically, a hole punch cloud with ice in the center, and an ice canal in an Altocumulus cloud layer can be readily seen on the new International Cloud Atlas submission site, now closed. They’ve mistakenly, IMO, referred to “ice canal” photos as “distrails” without mentioning the ice canal “cirrus” down the middle. Formerly, distrails were clearings produced by aircraft in thin clouds without any change of phase in the cloud induced by the aircraft, unlike those holes and clearings produced when the ice-phase is triggered by an aircraft passage.

Certainly a “hole punch” cloud is not a distrail, a linear feature, and should have a separate nomenclature.

In keeping with the new terminology regarding “anthro” effects, maybe it should be, since we’re talking about the Cirrus induced by an aircraft, albeit at much lower levels than true Cirrus clouds:

“CIrrus Altocumuloanthroglaciogenitus.” (??)

Here’s a classic one of those that erupted over Catalina, posted here last January:

11:27 AM, January 2nd. The ice canal in the middle of an Altocumulus layer that might in the future be termed a Cirrus altocumuloanthroglaciogenitus.

5:53 PM. An example of the various cirriform clouds we’ve been treated to the past week or two, ones that have been giving us those nice sunrises and sunsets. Doesn’t seem like there’s been a cloud below 50,000 feet for about that long, too. (I’m exaggerating just a little.)7:04 PM. Seems like sunsets are occurring later and later. Here the setting sun allows some of the “topography” of Cirrus clouds to be accentuated.

The End

——————————————-1It should be pointed out immediately if not sooner that Catalina’s Cloud Maven Person had plenty of time to rectify, or suggest changes to the Atlas as he could have been part of this process, but didn’t really do anything except submit some images for consideration.